Polymethine dyes



Patented Apr. 23,1946.

UNITED STATES PATENT "OFFICE amass Company, Rochester, N. Y., acorporation of New Jersey No Drawing.

Application September 1, 1942, Serial No. 458,927

110mm. (01. zoo-cm This invention relates to polymethine dyes and to aprocess for the preparation thereof. This application is acontinuation-in-part 01' our copending application Serial No. 353.502,filed Ausust 21, 1940, now Patent N 2,317,357.

A number of cyanine dyes, merocyanine dyes, hemicyanine dyes and styryldyes are ,known. These dyes contain a chromophore comprising apolymethine chain, one end or which is attached to the nitrogen atom ofa hetenocyclic nucleus, and the other end of which is attached, in thecase of cyanine dyes, to the nitrogen atom of another heterocyclicnucleus; in the case of merocyanine dyes, to a carbonylic oxygen orsulfur atom; in the case of hemicyanine dyes. to the ni-- trogen atom ofan alkylamino or arylamino group; and in the case of styryl dyes, to thenitrcgen atom of a dialhylamino group, the hemicyanine and styryl dyesdiffering in that a part of .the polymethine chain in the styryl dyesconsists of the carbon atoms of an aromatic nucleus to which is attachedthe dlalkylamino group, whereas in hemicyanine dyes the polymethinechain does not pass through an aromatic nucleus.

We have no found that cyanine, hemicyanine, merocyanine and styryl dyescan be made, containine' a polymethine chain one end of which isattached to the nitrogen atom of a 3,4-trimethylenebenzothiazolenucleus. This nucleus diflers from the nitrogenous heterocyclic-nucleiin known dyes of these types, in that there is a bridge of atoms betweenthe nitrogen atom and another atom in the nucleus. Our new dyessensitize photographic silver halide emulsions, we have found.

It is, accordingly, an object of our invention to provide new dyes. Afurther object is to provide a process for preparing such dyes. Afurther object is to provide photographic emulsions sensitized with ournew dyes. Other objects will become apparent hereinafter.

In accordance with our invention, we provide cyanine dyes by condensing2-methyl-8,4-benzothiazolium quaternary salts with various substances.To prepare monomethine cyanine dyes, we condense a2 methyl 3,4benzothiazolium quaternary salt with a cyclammonium quaternary saltcontaining in the alpha or gamma position (i. e. one of the so-calledreactive positions) a halogen atom, such as iodine, or an alkylmercaptoadvantageously effected in the presence of an acid-binding agent, suchas triethylamine, N-

-methylpiperidine, pyridine or sodium carbonate.-

The condensations are advantageously effected in a medium, such asethyl, isopropyl or n-propyl alcohol, Heat accelerates thecondensations.

To prepare symmetrical trimethine cyanine (carbocyanine) dyes, wecondense a Z-methyl- 3,4-benzothiazolium quaternary salt with an esterof an orthocarhoxylic acid, e. g. ethyl orthoformate or ethylorthoacetate. The condensations are advantaaeouslyeflected in thepresence of an acid-binding agent, such as pyridine. celerates thecondensations.

To prepare unsymmetrical trimethine cyanine (carbocyanine) dyes, wecondense a 2-methyl- 3,4-benzothiazolium quaternary salt with acyclammonium quaternary salt containing, in a reactive position, ap-arylaminovinyl group, e. g. a ,6anilinovinyl or a p-acetanilidovinylgroup. The condensations are advantageously effected in the presence ofa basic condensing agent, such as triethylamine or piperldine. Thecondensaticns are advantageously efiected in a medium, such as ethyl,isopropyl or n-propyl alcohol. Heat accel-- erates the condenmtions.

Also, we have found that 2-methy1-3,4-benz0- thiazolium quaternary.salts can be condensed with diary] formamidines, such as diphenylformamidine, in the presence of a condensing agent, such as aceticanhydride, to give 2-(p-acylarylamino) -3,4-trimethylene benzothiazoliumquaternary salts which in turn can be condensed, in

- the presence of an acid-binding agent, with cyor arylmercapto group.The condensations are so clammonium quaternary salts containing, in areactive position, a methyl group, e. g. Z-methylbenzoxazole alkiodides,2-methyl-benzothiazole alkyl-p-toluenesulionates,Z-methyl-fl-naphthothiazole alkiodides, quinaldine alkiodides, lepidinealkiodides and 2-methyl-3,4-trimethylenebenzothiazolium iodide, to givecarbocyanine dyes.

We have also found that 2-methyl-3,4-benzothiazolium quaternary saltscan be condensed with ,s-arylaminoacrolein anil salts, such asanilinoacro'lein anil hydrochloride, in the presence oi. a condensingagent such as acetic anhydride, to give2-(4-acylarylamino-1,3-butadienyl)-3,4-trimethylenebenzothiazoliumquaternary salts which in turn can be condensed, in the Heat ac presenceof an acid-binding agent, with cyclammonium salts containing in areactive position, a methyl group, e. g. z-methylbenzoxazole alkiodides,Z-methylbenzothiazole alkiodides, 2-methyl-o-naphthothiazolealkyl-p-toluenesultonates, quinaldine alkiodides, lepidine akiodides and2- methyl-3,4-trimethylenebenzothiazolium iodide, to give pentamethinecyanine (dicarbocyanlne) dyes.

Hemicyanine dyes can be prepared from the -aforesaid2'-(B-acylarylamino)- and 2-(4-acylarylamino-1,3-hutadienyl) -3,4trimethylenebenzothiazolium quaternary salts by heating the quaternarysalts with amines such as aniline, n-primar butylamine, diethylamine,piperidine. morpholine and furfurylamine. The condensation isadvantageously carried out in a medium such as ethyl alcohol, npropylalcohol or isopropyl alcohol.

Merocarbocyanine and mcrodicarbocyanine dyes can be prepared bycondensing the aforesaid 2-(B-acylarylamino)- and2-(4-acylarylamino-1,3-butadienyl)-3,4-trimethylene benzethiazoliumquaternary salts with organic compounds containing a keto methylenegroup, such as B-alkyl rhodanines, .l-aryl rhodanines, Z-dialkyl amino-M5) -thiazolones, 2-diphenylamino- 4(5) -thi azolone,3-alkyl-2-thio-2,4(3,5) -oxazolediones, 1,3-diphenyl-2-thi0hydant0in,lpheny1- 3-alkyl-5-thiopyrazolones, 3-alkyl-1-phenyl-2- thiohydantoins,2-thiobanbituric acids, benzoyl acetonitrile and cyano acetanilide. Thecondensations are advantageously carried out in the presence of anacid-binding agent such as triethylamine or piperidine in a medium suchas ethyl alcohol n-propyl alcohol or isopropyl alcohol.

Styryl dyes can be prepared Way condensing 2-methyl-3,4-trimethylenebenzothiazolium quaternary salts with dialkylamino benzaldehydes anddialkylamino cinnamic aldehydes. The condensation are advantageouslycarried out using a catalyst such as diethylamine or piperidine in amedium such as ethyl alcohol, n-propyl alcohol or isopropyl alcohol.

The following examples will serve to illustrate our new dyes and themanner of obtaining the same.

Example 1.1 -ethyl-3,4-trimthylene-thia-2'- cyanine iodide 0.9 g. (1mol.) of 2-methyl-3,4-trimethylenebenzothiazolium triiodide and 2.23 g.(3.6 mol.) of z-phenylmercaptoquinoline ethiodide were placed in cc. ofpyridine. The mixture was boiled, under reflux, for 15 minutes. Theresulting brownish solution was chilled to 0 C. The dye was filteredoff, washed with water, acetone and then methyl alcohol, and then driedin the air. In this manner 0.5 g. (68% yield) of dye was obtained. Aftertwo recrystallizations from methyl alcohol (320 cc. per gram of dye) thedye was obtained, in 40 percent yield, as orange felted needles, meltingat 286 to 287 C. with decomposition. A solution of the dye in methylalcohol is yellowish brown. The dye sensitized a photographic gelatinosilver bromiodide emulsion moderately strongly to 555 mu, with a maximumat about 510 mu.

In a. similar manner, 2-methyl-3,4-trimethylenebenzothiazoliumquaternary salts can be condensed with 2-methylmercaptobenzothiazoleethiodide, 2-phenylmercaptobenzothiazole ethiodide and'i-phenylmercaptopyridine ethiodide.

Example 2.-3-ethyZ-3,4-trimethylene-oxathiacarbocyanine iodide 1.0 g. (1mol.) of 2-methyl-3,4-trimethylenebenzothiazolium triiodide and 1.37 g.(1.8 mol.) of 2 -(fi-acetanilido vinyl) benzoxazole ethiodide wereplaced in 15 cc. of pyridine. The mixture was boiled, under reflux, for15 minutes. The reaction mixture was cooled and the dye filtered oil.The dye was washed well with methyl alcohol and dried in the air. 0.5 g.of crude dye (58 percent yield) was thus obtained. To reduce anydye-triiodide present to the monoiodide, the dye was dissolved in hotmethyl alcohol and sulfur dioxide was slowly bubbled through thesolution. The solution was cooled and the dye filtered oil. The dye wasthrice recrystallized from methyl alcohol and obtained, in 12. percentyield, as reddish needle having a blue reflex and melting at 258 to 259C. with decomposition. Its methyl alcoholic solution was orange. Itsensitized a photographic gelatino-silver-bromiodide emulsion stronglyout to 605 mu with a maximum at 550 mu.

In a similar manner, 2-methyl-3,4-trimethylenebenzothiazolium iodide canbe condensed with 2-(p-acetanilidovinyl) benzothiazole ethiodide,2-(1s-acetanilidovinyl)-thiazoline methiodide 0r 4-(p-anilinovinyl)-quinoline ethiodide.

1.1 g. (2 mol.) of Z-methyl-3,4-trimethylenebenzothiazolium iodide and0.98 g. (1 mol.+300 percent excess) of ethyl orthoformate were placed in30 cc. of pyridine. The mixture was refluxed for 45 minutes. The dyeseparated from the hot reaction mixture. The mixture was cooled and thedye filtered oif, washed well with methyl alcohol and dried in the air.In this manner, 0.75 g. (83 percent yield) of crude dye were obtained.It was recrystallized from methyl alcohol (710 cc. per gram of dye) andobtained, in 50 percent yield, as a felt of purplish crystals, meltingat 308 to 309 C. with decomposition. Its

methyl alcoholic solution was bluish red. It seniodide emulsion to about590 mu with maximum sitized a photographic gelatino-silver-bromiodidesensitivity at 540 mu. emulsion strongly out to 680 mu, with a maximumat about 595 mu. Example 7.3-ethul-5-[(3,4-trimethylene-2(3) 5benzothiozolylidene) -ethylidenel -rhodanine Example4.-2-(p-acetanilidovinyl)-3,4-trimethylenebenzothiazolium iodide s /1\1\ can C1HtN3 l\/7\c 6 10 J 50=on-0n=c2 5 2CCH=OHN\ 3 \3/ 45 4 3% cm 8 NI "34, CH: H2 H2 \0 \CQQ 15 11, A mixture of 3.2 g. (1 mol.) of2-methyl-3,4- 0.3 g. (1 mol.) of -acetanilidomethylene-3trimethylene-benzothiazolium iodide and 2.4 g. ethylrhodanine, 0.32 g.(1 mol.) of 2-methyl-3,4- (1.2 mol.) of diphenylformamidine in 10 cc. oftrimethylenebenzothlazolium iodide and 0.145 cc. acetic anhydride wasrefluxed gently over a free 20 (1.05 mol.) of triethylamine were placedin cc. flame for 5 minutes. Upon cooling the mixture, of absolute ethylalcohol. The mixture was boiled, the dark brown acetanilido compoundcrystallized under reflux, for minutes. The reaction mixout. It wasfiltered off, collected on a filter and ture was cooled, the dyefiltered off, washed with washed with methyl alcohol and diethyl ether.methyl alcohol and dried in the air. In this man- Yield 3.4 g., '74percent. her 0.25 g. (70 percent yield) of dye were obtained. The dye,after two recrystallizations from xa ple -weidni id0-1,3-b'uia eny a.mixture of pyridine and methyl alcohol was ob- 3. ri hzll n z t i ziodide tained in 42 percent yield, as reddish crystals melting at 288 to289 C. with decomposition. .7 can A solution of the dye in methylalcohol is pink. 6 The dye sensitized a photographic gelatino-sil- 5ver-bromiodide emulsion strongly out to 625 mu 4 3 00cm with a maximumat about 595 mu.

I In a similar manner, 2-methyl-3,4-trimethyl in 0H, enebenzothiazoliumiodide was condensed with a I5-acetani1ido-methylene-3-ethyl-2-thio-2,4(3,5)-

oxazoledione to give 3-ethyl-5-[(3,4-trimethyl- A mixture f 32 (1 mol of2 methy1 3 4 ene- 2(3) -benzothiazolylidene) ethylidenel-2-trimethylenebenzothiazolium iodide and 2.5 g. (1 .5 0 0 in a yield of 74p mol.) of fi-anilinoacrolein anil hydrochloride in Cent The y after tWOrecrystallizations f o 50 cc. of acetic anhydride was refluxed for aPyrid ne met yl alcohol mix ure Was obtained minutes. The hot solutionwas filtered to remove s reddish c s. m t ng at 87 to 288 0. A a smallportion of dark brown solid which was Solution f the y in yl c l wasediscarded. After cooling the filtered solution and 45 The dyesensitized a photographic l -s diluting it with 350 cc. of diethylether, the acetver-bromiodide emulsion strongly O o 630 anilido compoundseparated out. It was collected t a maximum at about 570 mu.

on a filter, washed with methanol and diethyl ether and dried. Yield:3.8 g., 79 percent. Example 8' 3'methyl'1 WWW/1'44 (314'mmeth'mane-2(3)-benzothiazolylidene) ethylidenel-5- Example6.--2-(4-anilino-1,3'-butadienyl) -3,4- 11111113010116trimethylenebenzothiazolium iodide 4 3 4 3 H CH3 H2O (En, El H:

A mixture of 1.6 g. (1 mol.) of 2-fl-acetanilido- 3.8 g. (1 mol.) of theacetanilido compound of vinyl-3,4-trimethylenebenzothiazolium iodide,0.6 the preceding example and 1.1 cc. (approximateg. (1 mo -me y -Dh y1--D r Z0l0n and ly 1.5 mol.) of aniline in 20 cc. of absolute ethyl 0.46cc. (1 mol.) triethylamine in 25 cc. absolute alcohol were refluxed for15 minutes. The soluethyl alcohol was refluxed 15 minutes. The reaction,after a few minutes, rapidly assumed a redtiOn mixture W s Chilled a d eye collected on dish orange coloration. Upon cooling, the anilino afilter and washed with methanol. Yield: 1.15 g., compound separated out.It was -filtered oil? and 92 percent. It was obtained as minute redcryswashed with methanol. Yield: 2 g., 57 percent. tals, melting at 238to 239 C. without decompo- The dye, after two recrystallizations frommethyl sition, after an extraction with cc. hot methalcohol cc. per gramof dye) was obtained anol and recrystallization of the residue from asbrownish crystals having a blue reflex, melting methyl alcohol (400cc./g.). A solution of the dye at 247 to 248 C. with decomposition. Asolution in methyl alcohol is orange. The dye sensitized a of the dye inmethyl alcohol was orange. The photographic gelatino-silver-bromoiodideemuldye sensitized a photographic gelatino silver brom 75 sion to 570 muwith a slight maximum at 530 mu.

O C-NH A mixture of 1.6 g. (1 mol.)-B-acetanilidovinyl-3,4-trimethylenebenzotluazolium iodide, 0.5 g. (1moL) thiobarbituric acid, and 0.46 cc. (1 mol.) triethylamine in 50 cc.absolute ethyl alcohol was refluxed for 15 minutes. The dye separatedfrom the hot solution. After cooling it was collected on a filter andwashed well with methanol. Yield: 1.15 g., 100 percent. The veryinsoluble dye was extracted with 100 cc. hot pyridine and filtered. Theresidue 1.0 g. was extracted a second time with 250 cc. hot pyridinefrom which on cooling 0.1 g. of dye separated.

The first extract was discarded. The crystallized portion as well as theresidue had a melting point greater than 325 C. and solutions of bothportions in pyridine are orange. The dye is a weak sensitizer. Itsensitized a photographic gelatino-silver-bromoiodide emulsion to 550 muwith no maximum sensitization.

Example 1 0.3 -ethyl-1 -phenyl- (3,4-tri1nethyZene-Z (3)-benzothiazolzrlidene) ethylidene1-2- thz'ohydantoin A mixture of 0.4 g.(1 mol.) 2-p-acetanilidovinyl-3,4-trimethylenebenzothiazolium iodide,0.2 g. (l moi.) 3-ethyl-l-phenyl-2-thiohydantoin, and 0.12 cc. (1 mol.)triethylamine in 15 cc. absolute ethyl alcohol was refluxed 20 minutes.The reaction mixture was chilled. The dye was collected on a filter,washed well with methanol. Yield: 0.3 g., 82 per cent. It was obtainedas purplish crystals with blue reflex, melting at 246 to 247 0. withoutdecomposition, after one extraction with 30 cc. hot methanol andrecrystallization of the residue from a pyridine methyl alcohol mixture.A solution of the dye in acetone is orange. The dye, a strongsensitizer, sensitizing a photographic gelatino-silver-chlorobromideemulsion between 470 mu and 620 mu with a maximum at 580 mu.

Example 11 .-3-ethyl-1 -phenul-5- (3,4-trimethylene 2(3)beneothiaeolylidene) butenylidene] -2-thiohydantoin s OC-NEtC=CHCH=CH-CH= cs \III Ih Hg CH2 A mixture of 0.5 g. (1 mol.)2-(4-anilino-1,3- butadienyl) 3,4 trimethylenebenzothiazolium iodide and0.3 g. (1 mol.) 3-ethyl-l-phenyl-2- thiohydantoin in 25 cc. pyridine wasrefluxed gently over a free flame for 45 minutes. The pyridine solutionassumed a bluish red coloration alter 5 to minutes heating. The solventwas removed under diminished pressure by heating on the water bath. Theresidue was suspended in 20 cc. cold ethyl alcohol, collected onafilter, washed with methanol. Yield: 0.2 g., 50 per cent.

The dye was obtained as blue crystals, melting at 265 to 266 0. withoutdecomposition, after an extraction with 20 cc. hot methanol andrecrystallization of the residue from a pyridine methyl alcohol mixture.Solution of the dye in acetone is purple. The dye sensitized aphotographic silver bromoiodide emulsion from 560 mu to 730 mu with amaximum at 675 mu.

Example 12. Z- (p-dimethy laminostyryl) -3,4-

trimethylenebenzothiazolium iodide resulting mixture was refluxed for 4hours.

The dye separated from the bluish red solution. After cooling, the dyewas collected on a filter, washed with methyl alcohol and dried in theair. 1.0 g. (71 percent) yield of dye, was obtained. After threerecrystallizations from methyl alcohol (250 cc. per gram of dye), thedye was obtained, in 35 percent yield, as dull purplish crystals. Asolution of the dye in methyl alcohol was bluish red. The dye sensitizeda photographic gelatino-silver-bromiodide emulsion weakly out to about630 mu, with an ill-defined maximum at about 590 mu.

In a similar manner p-diethylamino-benzaldehyde and otherdialkylamino-benzaldehydes and dialkylamino cinnamic aldehydes can becondensed with our new quaternary salts.

In the preparation of photographic emulsions containing our new dyes, itis only necessary to disperse the dyes in the emulsions. The methods ofincorporating dyes in emulsions are simple and well known to thoseskilled in the art. It is convenient to add the dyes from solutions inappropriate solvents. Methanol has proven satisfactory as a solvent forour new dyes. Ethyl alcohol or acetone may also be employed where thesolubility of the dyes in methanol is lower than desired.

Sensitization by means of our new dyes is, of course, directed primarilyto the ordinarily employed geiatino silver halide developing outemusions. The dyes are advantageously incorporated in the washed,finished emulsions and should, of course, be uniformly distributedthroughout the emulsions.

. The concentration of our new dyes in the emulsion can vary widely, i.e. from about 5 to about mgs. per liter of fiowabie emulsion. Theconcentration of the dye will vary according to the type oflight-sensitive material in the emulsion and according to the efiectsdesired. The suitable and most economical concentration for aaoaaaa anygiven emulsion will be apparent to those skilled in the art upon makingthe ordinary tests and observations customarily used in the art ofemulsion making.

To prepare a gelatino-silver-halide emulsion sensitized with one of ournew dyes, the following procedure is satisfactory. A quantity of the dyeis dissolved in methyl alcohol or other suitable solvent and a volume ofthis solution (which may be diluted with water) containing from 5 to 100mgs. of dye is slowly added to about 1000 cc. of agelatino-silver-halide emulsion, with stirring. Stirring is continueduntil the dye is uniformly distributed throughout the emulsion. Withmost of our new dyes, 10 to 20 mgs. of dye per liter of emulsionsullices to produce the maximum sensitizing eiiect with the ordinarygelatino silver bromide (including bromiodide) emulsions. Withfine-grain emulsions, which includes most of the ordinarily employedgelatinosilver-chloride emulsions, somewhat larger concentrations of dyemay be necessary to secure the optimum sensitizing effect.

The above statements are only illustrative and are not to be understoodas limiting our invention in any sense, as it will be apparent that ournew dyes can be incorporated by other methods in many of thephotographic silver halide emulsions customarily employed in the art.For instance, the dyes may in incorporated by bathing a plate or filmupon which an emulsion has been coated, in the solution of the dye, inan appropriate solvent. Bathing methods, however, are not to bepreferred ordinarily.

The 2-methyl-3,4-trimethylenebenzothiazolium quaternary salts employedherein can be prepared by oxidizingl-thioacetyl-1,2,3,4-tetrahydroquinoline with a halogen such as bromineor iodine, as described in our copending application, Serial No.353,502, filed August 21, 1940, now Patent No.-

What we claim as our invention and desire to be secured by LettersPatent of the United States is:

1. The cyanine dyes represented by the following general formula:

wherein L represents a methine group, n represents a positive integer offrom 1 to 3, d represents a positive integer of from 1 to 2, R,represents an alkyl group, X represents an anion, and Z represents thenon-metallic atoms necessary to complete a heterocyclic nucleuscontaining from 5 to 6 atoms in the heterocyclic ring.

2. The carbocyanine dyes represented by the following general formula:

wherein R represents an alkyl group and X represents an anion.

3. The carbocyanlne dyes represented by the folio general formula:

/o=cn-cn=cu-c\ l| l X-N R "2k H2 10 Cfia wherein R represents an alkylgroup and X represents a halide anion.

4. The carbocyanine dyes represented by the following general formula:/O S\ c=cu cn=ouo 1 1 X-N/ 0211 rm on,

(-lh wherein X represents a halide anion.

5. The carbccyanine dye represented by the fol-- lowing formula:

S O /c=cn-cn=on-o T I-I? C3H5 H20 H2 CH3 6., The carbocyanine dyesrepresented by the following general formula:

s s c=ou-ou=on-o x X N H: CH2 H26 CH2 C 3 C 2 wherein X represents ananion. 7. The carbocyanine dyes represented by the following generalformula:

8 s G=CHCH=CHC i X N H: CH: 119% B3 0 3 CH1 wherein X represents ahalide anion.

8. The carbocyanine dye represented by the following formula:

s s o=cn-on=ono h/ t H: CH: H2 CH1 C i \C 1 9. The monomethine cyaninedyes represented by the following general formula:

s ocn I I N N/ R/ x H:O\ (3H, 7 C

wherein R represents an alkyl group and X repre- 11. The monomethlnecyanlne dye represented sents an anion. by the following formula:

10. The monomethine cyanine dyes represented CQHI X 10 by the followinggeneral formula: s

/c=cnm N aI| H: (5H,

H1 H: c, wherein X represents a halide anion.

LESLIE G. S. BROOKER. HOMER W. J. CRESBMAN.

